Java Kickstart for Test Developers, 17-19 December 2012

Objects

• fields: properties (some immutable, some mutable)
• methods: behavior (may affect the mutable state)
• identity:
  • reference identity: based on memory location, using ==
  • structural identity: based on object fields, using .equals(). Only immutable (final) fields should be used for this.

Unit Testing

White-box, specifying behavior for the smallest atomic chunks of code.

• positive testcases: things work as expected
• negative testcases: things fail as expected

Collections

Important ones:

• Collection<E>
  • List<E>
    • ArrayList<E>
    • LinkedList<E>
  • Set<E>
    • HashSet<E>
    • SortedSet<E>
      • TreeSet<E>
• Map<K, V>
  • HashMap<K, V>
  • SortedMap<K, V>
    • TreeMap<K, V>

Concurrency

Benefits:

• parallelism (multithreading): ability to do multiple things at the same time
• performance: things don't have to wait for each other
• resource utilization: take advantage of multi-core / multi-processor hardware

Problems:

• race conditions: two threads are trying to modify shared memory or shared resources simultaneously
• deadlocks: two or more threads with a lock graph cycle
• thread starvation: one thread acquires a lock and holds it forever, or thread scheduler is never allowed to context switch

Solutions:

• monitors (locks / mutexes / critical sections), synchronized methods or blocks
• semaphores (wait + notify)
• ... better solutions: BlockingQueue and other utilities in java.util.concurrent

Videos

Day 1

• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/1.1.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/1.2.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/1.3.mov

Day 2

• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/2.1.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/2.2.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/2.3.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/2.4.mov

Day 3

• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/3.1.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/3.2.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/3.3.mov
• https://mrkn.s3.amazonaws.com/recordings/java-kickstart-20121217/3.4.mov

Resources

• "Effective Java"
• "Java Concurrency in Practice"
• "Design Patterns"